Fig. 4

a Loupe view of the lesion demonstrates seminoma components (arrowheads) lying along multilocular cysts (asterisks indicate cystic space). Arrows indicate thymus (HE stain). b Close view of the cyst wall shows solid sheets of tumor cells with lymphocytic infiltrates. Asterisk indicates cystic space (HE stain, ×200). c Cluster of seminoma cells has oval nuclei with surrounding pale cytoplasm (HE stain, ×400). d Cysts (asterisk) were lined by nonneoplastic squamous epithelium, and no seminoma cells were located on the surface of cysts (HE stain, ×400). e Tumor cells are positive for PLAP (left) and OCT3/4 (right)